Supported metal catalysts are used in various fields such as petrochemistry, oil refining, environmental products and fuel cells. In polymer electrolyte fuel cells (PEFCs), research and development are focusing on electric vehicles, stationary cogeneration and power for portable devices.
The electrocatalyst may consist of an active metal based on platinum supported on a carrier of a conductor such as carbon and so on. The catalyst performance depends on the degree of dispersion of the active metal. For a given amount of active metal, catalyst performance increases with increasing surface area. In order to reduce the loading amount of expensive platinum, the catalyst should preferably be used in particulate form. Hence, a highly dispersed catalyst is desired.
The electrocatalyst may be manufactured, as shown for example in the following Patent Reference 1, by reducing a chloroplatinic acid solution to prepare a metal colloidal solution, followed by supporting it on a carrier. A method for producing an alloy catalyst with platinum is shown, for example in the following Patent Reference 2, wherein alloy particulates are obtained by reducing an organic protecting agent with alcohol.    Patent Reference 1: JP-A 2001-224968,    Patent Reference 2: JP-A 2003-226901
In addition to reducing platinum as described above, in fuel electrodes (anode), the use of an alloy catalyst to increase carbon monoxide poisoning tolerance is now being studied. An alloy catalyst is important not only in fuel electrodes but also to improve the oxygen reduction activities at air electrodes(cathode). Examples of an alloy catalyst are platinum with iron, cobalt and ruthenium.
In the conventional manufacturing method of an alloy catalyst, a metal salt solution was added on platinum particles already supported on carbon by an impregnation process etc., followed by reducing at a high temperature of about 900° C. When the particles were supported on carbon using a metal salt as the metal, an alloy was manufactured by reduction with an alcohol. However, in the alloy catalyst obtained by such a process, the particle size of the catalyst particles might be irregular, the composition of each particle might not be uniform due to the difference in reducibility, aggregation of platinum particles might take place due to high temperature heating, and a catalyst containing highly dispersed nano-level particles could not then be obtained.